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‘Natural ecosystems could be playing a significant role in off-setting warming’ - new research

12 Jan 2012, 19:10

Verity Payne

flickr:HNDB

New research, to be published in the journal Science, suggests
that plants could be playing a vital role in counteracting man-made
climate change, by releasing chemicals into the atmosphere.

The science bit

For the first time, researchers have been able to detect
short-lived and highly reactive types of chemical known as 'Criegee
intermediates' or 'Criegee biradicals', which form when ozone and
hydrocarbons (chemicals consisting of hydrogen and carbon) react
together in the atmosphere.

Researchers have found that these chemicals react with sulfur
dioxide in the atmosphere, and these reactions, which happen very
quickly, play an important role in forming sulfate aerosols, which
in turn help shape the Earth's climate.

Scientists previously assumed a different chemical reaction was
the most important in forming sulfate aerosols, but these early
results suggest that this process - involving the Criegee
intermediates - could be as important, or even more so. Sulfate
aerosols affect the climate both by generating clouds and by
directly reflecting energy. How sulfate aerosols effect the climate
is a key area of uncertainty - and scientific research.

As Dr Carl Percival, Reader in Atmospheric Chemistry at The
University of Manchester and one of the authors of the paper puts
it:

"Our results will have a significant
impact on our understanding of the oxidising capacity of the
atmosphere and have wide ranging implications for pollution and
climate change."

What this means for the climate

Sulfate aerosols directly cool the atmosphere by reflecting some
of the Sun's energy out into space and stopping it from hitting the
planet, Earlier this year scientists suggested that sulfate
aerosols have slowed the temperature rise caused by man-made
greenhouse gas emissions over the last decade. This new research
suggests that Criegee intermediates may have played an important
role in this process.

And this could indicate another reason why preserving the
biosphere could be important to help keep man-made climate change
in check. Professor Dudley Shallcross, Professor in Atmospheric
Chemistry at The University of Bristol, points out:

"A significant ingredient required for the production of these
Criegee biradicals comes from chemicals released quite naturally by
plants, so natural ecosystems could be playing a significant role
in off-setting warming."

What it doesn't mean

When breakthrough science like this is published it can be
over-egged or even totally misinterpreted by the media and
blogosphere. For example, the headline "
Global Warming may be Defeated by Molecule Discovery" which the
International Business Times ran with is not helpful or accurate.
In light of that, here's what this paper does not show:

- It doesn't mean that global warming has been 'defeated'

No surprises there. The research does not suggest that we no
longer need to mitigate climate change, nor that it will cease to
be a problem.

- This isn't a geoengineering 'cure' for global warming

The paper describes preliminary work identifying a natural process
in the climate. An enormous amount of research would be needed and
a huge number of technical and political issues overcome before we
could work out how to harness this process for our own means.

- It doesn't mean that global warming has stopped

Last year's finding that sulfate aerosols have slowed man-made
warming provoked a mass of
misinformation, including the favourite claim of climate
skeptics that global warming has stopped. It hasn't, as we have
explained manytimes, and this
research says nothing to suggest that it has.

The takeaway message from this research? Chemicals released to the
atmosphere by plants could be playing an important role in limiting
man-made global warming, through the production of sulfate
aerosols.

We'll update the post if the paper gets any interesting media
coverage.